On Tue, Jan 17, 2012 at 06:27:19PM -0800, Linus Torvalds wrote: > On Tue, Jan 17, 2012 at 6:04 PM, Jamie Lokier <jamie@xxxxxxxxxxxxx> wrote: > > > > I think Indan means code is running with 64-bit cs, but the kernel > > treats int $0x80 as a 32-bit syscall and sysenter as a 64-bit syscall, > > and there's no way for the ptracer to know which syscall the kernel > > will perform, even by looking at all registers. It looks like a hole > > in ptrace which could be fixed. > > We could possibly munge the "orig_ax" field to be different for the > int80 vs syscall cases. That's really the only field that isn't direct > x86 state. And it's 64 bits wide, but we really only care about the > low 32 bits in the kernel. So a bit in the high bits that says "this > was a int80 entry" would be possible. That would be incompatible. However you could just add another virtual register with such information (in fact I thought about that when I did the compat code originally). However I don't think it'll salvage the original broken by design ptrace jailer. And everyone else so far has done fine without it. -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
